الفهرس 
Aim of the workOnly 14 pages are availabe for public view
 |  | from | 125 |  |  |
| | | from | 125 | | |
Abstract
Part (I): Introduction
It dealt with an overview of the sources of water pollution, especially dyes and industries based on their use, and the health hazards resulting from the discharge of water from those industries on the quality of water and living organisms in general. Thus, various techniques were used to remove different contaminants. But the adsorption technology was chosen because it has so many benefits over other approaches, and accordingly, the introduction dealt in some detail with the adsorbents of nanomagnetite in terms of preparation and means of protecting them from oxidation or assembly with multiple types of coatings, especially silica and surfactants, along with their respective characteristics. It also presented examples of the removal mechanisms of dyes under study. This is in addition to demonstrating the advantages of using a solvent-free microwave as a green, environmentally friendly, and safe method for preparing multi-application magnetic nano-adsorbents.
Chapter Two: It is the experimental part of the thesis
It included the types and sources of chemicals used and methods of preparing solutions, including two types of cationic dyes under study, namely Methylene blue- MB and Brilliant green- BG. In addition to their determination using UV-Vis spectrometer. It also includes a detailed explanation of a new method for preparing magnetite nanoparticles covered with silica Fe3O4NPs@SiO2 as well as magnetite nanoparticles covered with silica plus a surfactant (SDS) in the form of Fe3O4NPs@SiO2@C12 using microwave technique. This was achieved through direct interaction between the components of the adsorbent in equal weight ratios and in the absence of an organic solvent.
The synthesized nanomagnetite adsorbents were characterized using infrared spectroscopy (FT-IR), x-ray diffractometer (XRD), energy dispersive x-ray analyzer (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), in addition to thermal gravimetric analysis (TGA).
The factors affecting the adsorption process, including the pH of the medium, contact time, the adsorbent mass, as well as the concentration of the dye in the solution, were optimized to achieve the highest removal percentage of MB dye using Fe3O4NPs@SiO2 and BG dye using Fe3O4NPs@SiO2@ C12.
The adsorbents were applied to remove the cationic dyes added to natural water samples, including ground water, mineral water, sea water, river water, and tap water, in addition to reusing the adsorbent for more than one time.
This is in addition to studying the efficiency of the novel nanocomposite (Fe3O4 NPs@SiO2@C12) on preconcentrating traces of BG dye spiked environmental water samples for the purpose of its determination.
Chapter Three: It is related to the presentation and discussion of the results
This chapter is divided into two parts:
The first part: It concerns the results of preparing silica-coated magnetite nanoparticles (Fe3O4NPs@SiO2) as adsorbent and its optimization for the removal of MB dye from aqueous solutions. It was concluded:
The percentage of MB removal using Fe3O4NPs@SiO2 (prepared by mixing and grinding silica and magnetite at an optimal ratio of 1:1 and exposing to microwave radiation for 10 minutes at 200 watts) reached a maximum value of 95.3%, compared to 48% for magnetite alone.
The results of the characterization of Fe3O4NPs@SiO2 confirm the success of the new method of preparation, based on the results of:
- Infrared spectroscopy (FT-IR), which showed the presence of bands specific to the two components as well as the Fe―O―Si bond.
- X-ray diffraction (XRD), where new bands appeared in the range of 2θ = 15-30° for silica, in addition to the characteristic bands of magnetite diffraction.
- Scanning electron microscope (SEM), which showed a clear change in the external shape of the surface of the adsorbent compared to its components.
- Transmission electron microscope (TEM), where the size of the particles came to be in the nano range 11.7-24.8 nm.
- Energy dispersive x-rays (EDX) to confirm the purity of the prepared adsorbent, where the percentage of the constituent elements was as follows: 28.2% Fe, 46.58% O, 23.72% Si.
- Fe3O4NPs@SiO2 achieved the highest value for removing MB dye, which was 98.9% at the optimum values of pH = 11, contact time of 5 minutes, mass of 0.05 g, and dye concentration equal to 0.4x10-5M.
- The treatment of equilibrium experimental results showed that they were in agreement with Langmer’s monolayer model, with a dye removal capacity of 47.98 mg/g and a correlation coefficient of R2 = 0.9963.
- The kinetics of the adsorption process of the dye were in harmony with the pseudo-second-order, with a correlation coefficient of R2 = 0.9999, in addition to equal values for both qe,exp and qe,cal.
- It was possible to reuse Fe3O4NPs@SiO2 to remove MB for 6 consecutive times (sorption-desorption) in a fast and easy way using ethanol and an external magnetic field.
- It was possible to successfully use Fe3O4NPs@SiO2 to remove 4 x 10-5M (12.8 ppm) concentration of MB dye spiked different samples, including tap water, river water, mineral water, and sea water, averaging 92.4–95.2% for fresh water after one or two cycles at most, and 94.3% for removal from saline water after three successive cycles.
Part Two: It concerns the results of preparing silica-coated magnetite nanoparticles with a surfactant (SDS) in the form of Fe3O4NPs@SiO2@C12 as adsorbent and its optimization for removal of BG dye from aqueous solutions. It was concluded:
The percentage for the removal of BG using Fe3O4NPs@SiO2@C12 (prepared by mixing and grinding each of the silica-coated manganite and SDS in an optimal ratio of 1:1 and exposing to microwave radiation for ten minutes at 700 watts) reached a maximum value of 96.6% compared to 68% of the silica-coated magnetite without adding SDS.
The results of the characterization of (Fe3O4NPs@SiO2@C12) confirm the success of the new method of preparation and the covalent bonding of the hydrocarbon chain to the silica surface in the form of C12, based on the results of:
- Infrared spectra (FT-IR), which showed the presence of bands specific to the two components as well as the Fe―O―Si bond and methylene groups (−CH2−) characteristic of the surfactant molecule (SDS) and the disappearance of the characteristic bands of the sulfate group.
- X-ray diffraction (XRD), where new bands appeared in the range of 2θ = 12–26° for silica in addition to the bands of magnetite and SDS diffraction.
- Scanning electron microscope (SEM), which showed a clear change in the external shape of the surface of the adsorbent compared to its components.
- Transmission electron microscope (TEM), where the size of the particles came to fall in the nanoscale range 11.7–21.8 nm.
- Energy dispersive x-rays (EDX) to confirm the purity of the prepared adsorbent, which reached 100% for the constituent elements as follows: 17.1% Fe, 38.17% O, and 14.84% Si, in addition to 29.89% C with no trace of sulfur.
- Thermogravimetric analysis (TGA) showed the stability of the adsorbent prepared by thermal microwave technique in the range 20-600°C compared to the adsorbent prepared by ionic bonding method of SDS, which dissociated at 206°C.
- (Fe3O4NPs@SiO2@C12) achieved the highest value for BG removal, reaching 98.33% at the optimum values of pH = 5.6, contact time of 5 minutes, mass of 0.07 g, and dye concentration of 30 ppm. This is in addition to the stability of the removal value at a wide range of pH (3–10).
- It demonstrated high stability in solutions containing varying concentrations of sodium chloride (0–1 M) with no significant change in removal efficiency, confirming the (−CH2−)12 group’s covalent bonding to silica.
- The treatment of equilibrium experimental results showed that they were consistent with Langmer’s monolayer model, with a dye removal capacity of 158.7 mg/g and with a correlation coefficient of R2 = 0.9791.
- The kinetics of the adsorption process of the dye was homogeneous with the pseudo-second-order with a correlation coefficient of R2 = 0.9999.
- It was possible to reuse (Fe3O4NPs@SiO2@C12) to remove BG for 6 consecutive times in an fast and easy way using ethanol and in the presence of an external magnetic field.
- It has been possible to successfully use Fe3O4NPs@SiO2@C12 to remove different concentrations of BG (25, 50 ppm) spiked samples of tap water, river water, groundwater, mineral water, and sea water, where the recovery rate reached 96.5-98.2%.
- The optimum conditions for the preconcentration method for traces of BG dye using Fe3O4NPs@SiO2@C12 were determined. A 150 ml initial sample volume was eluted to become 3 ml of ethanol with stirring time two minutes. Therefore, the preconcentration factor achieved was 50. A good linear dynamic range of concentrations 10–340 μg/L was obtained with a high correlation coefficient 0.9974, a detection limit 5.5 𝜇�g/L and limit of quantification 18.3 𝜇�g/L.
- The recovery percentage ranged (93.2-95.4%) obtained when applying the previous method for trace concentrations of (20 and 60 𝜇�g/L) BG dye spiked real water samples.
- Comparing the synthesis method of the two new magnetic nano-adsorbents using the microwave solvent-less method showed the ease and shortness of synthesis time compared to other modern multistep methods. It was also distinguished by its fast removal and reuse when applied.